Thanks to Yunomi for the strategy of waiting until the end to get the following items: giant tornado, giant/large whirlpools, giant ice floes, and big icebergs.
I discovered that jumbo clouds could be rolled up starting at 2400m. I dashed into 2 of them simultaneously at 2958m, which caused a glitch that added more to final size than rolling them up one at a time. There's nothing special about 2958m; I'm just pointing out when I dashed into 2 jumbo clouds. It should be more effective when done earlier, although you won't be able to reach the 2 clouds much before 2700m. Doing it then would mean getting the Queen later than usual, and it's unknown whether that would be good or bad. This strategy is very effective in Katamari Forever's version of this level (MAS 11), in which it's possible to jump into both clouds at 2400m. See sloobro's KF videos at YouTube for further details.
The Queen can be rolled up at 2727m, and the Flying King at 3089m. Several people, including sloobro, discovered this strategy independently.